1. Technical Field
The present invention relates to a liquid ejecting head, a liquid ejecting head unit and a liquid ejecting apparatus which eject liquid through nozzle openings, in particular, relates to an ink jet recording head, an ink jet recording head unit and an ink jet recording apparatus which discharge ink as liquid.
2. Related Art
For example, as disclosed in JP-A-2008-55716, there is an ink jet recording head in which viscosity of ink is lowered by heating the ink in an ink supply path in order to discharge high viscous ink represented by UV ink. In the ink jet recording head disclosed in JP-A-2008-55716, a liquid flow path through which heated water for heating ink is flown is provided in the head so that ink having lowered viscosity is stably flown through an ink supply path. Therefore, an excellent ink discharging characteristic can be obtained.
In the ink jet recording head disclosed in JP-A-2008-55716, ink is heated by heated water which has been heated by a heater provided outside the head. Therefore, the temperature of the ink is easily changed due to the influence by external environment before the ink reaches to pressure generation chambers in the head. Accordingly, the temperature of ink in the head cannot be made to be a desired temperature in some case even when the temperature of the heated water is controlled with a sensor provided outside the head. In such a case, there arises a problem that ink cannot be made to have desired viscosity so that an excellent discharging characteristic cannot be obtained.
It is to be noted that such problem arises not only in an ink jet recording head which discharges ink having high viscosity but also in an ink jet recording head which discharges ink after viscosity of the ink is lowered by heating the ink. Further, the above problem also arises not only in an ink jet recording head which discharges ink but also in a liquid ejecting head which discharges liquid other than ink.